Effectiveness of disinfectant treatments for inactivating Piscirickettsia salmonis

The potential of biomass-derived bio-liquid to prevent the spread of SARS-CoV-2 from waste and its production-based life cycle assessment

COVID-19 pandemic caused a significant increase in medical and infected domestic waste, greatly increasing risk of human infected with SARS-CoV-2. Therefore, it is critical to prevent the spread of SARS-CoV-2 from solid waste to humans. Current commercial disinfectants present a high carbon footprint issue. Hence, we prepared a renewable wheat straw-based bio-liquid that can damage SARS-CoV-2 RNA and protein. The wet thermochemical extraction (WTE) bio-liquid, with total organic carbon concentration exceeding 1892 mg/L, could effectively damage the virus. However, dry thermochemical extraction (DTE) samples were not efficient due to their low content of effective compounds. The life cycle assessment showed that WTE bio-liquid production implies lower energy and environmental negative impacts than DTE. Moreover, the process by-product, char, can simultaneously reduce 3.1 million tonnes of global CO₂ emissions while used as coal substitute. Yield of bio-liquid extremely exceed commercial disinfectant with just 1 % wheat straw utilisation, which meet the demand of processing solid waste. Further, their costs are significantly lower than commercial disinfectants, which are suitable for developing countries. Therefore, the antiviral bio-liquid produced from agricultural straw can be a new way to meet the needs of preventing the spread of SARS-CoV-2 and resume the sustainable development of society.

Bacterial Pathogenesis in Various Fish Diseases: Recent Advances and Specific Challenges in Vaccine Development

Aquaculture is a fast-growing food sector but is plagued by a plethora of bacterial pathogens that infect fish. The rearing of fish at high population densities in aquaculture facilities makes them highly susceptible to disease outbreaks, which can cause significant economic loss. Thus, immunity development in fish through vaccination against various pathogens of economically important aquaculture species has been extensively studied and has been largely accepted as a reliable method for preventing infections. Vaccination studies in aquaculture systems are strategically associated with the economically and environmentally sustainable management of aquaculture production worldwide. Historically, most licensed fish vaccines have been developed as inactivated pathogens combined with adjuvants and provided via immersion or injection. In comparison, live vaccines can simulate a whole pathogenic illness and elicit a strong immune response, making them better suited for oral or immersion-based therapy methods to control diseases. Advanced approaches in vaccine development involve targeting specific pathogenic components, including the use of recombinant genes and proteins. Vaccines produced using these techniques, some of which are currently commercially available, appear to elicit and promote higher levels of immunity than conventional fish vaccines. These technological advancements are promising for developing sustainable production processes for commercially important aquatic species. In this review, we explore the multitude of studies on fish bacterial pathogens undertaken in the last decade as well as the recent advances in vaccine development for aquaculture.

Aquaculture industry: Supply and demand, best practices, effluent and its current issues and treatment technology

The aquaculture industry has become increasingly important and is rapidly growing in terms of providing a protein food source for human consumption. With the increase in the global population, demand for aquaculture is high and is estimated to reach 62% of the total global production by 2030. In 2018, it was reported that the demand for aquaculture was 46% of the total production, and with the current positive trends, it may be possible to increase tremendously in the coming years. China is still one of the main players in global aquaculture production. Due to high demand, aquaculture production generates large volumes of effluent, posing a great danger to the environment. Aquaculture effluent comprises solid waste and dissolved constituents, including nutrients and contaminants of emerging concern, thereby bringing detrimental impacts such as eutrophication, chemical toxicity, and food insecurity. Waste can be removed through culture systems, constructed wetlands, biofloc, and other treatment technologies. Some methods have the potential to be applied as zero-waste discharge treatment. Thus, this article analyses the supply and demand for aquaculture products, the best practices adopted in the aquaculture industry, effluent characteristics, current issues, and effluent treatment technology.

Motile Aeromonas septicemia in tambaqui Colossoma macropomum: Pathogenicity, lethality and new insights for control and disinfection in aquaculture

Tambaqui Colossoma macropomum is the most produced native fish in South America. Besides the lack of knowledge regarding bacteria-stricken diseases, the unappropriated using of off-label therapies are common. In this study, Aeromonas hydrophila pathogenicity for tambaqui was first established by Koch's Postulate. Lethal doses (LD) were settled for investigation of clinical signs and mortality. The antimicrobial activities were investigated by disk-diffusion test against 11 antibiotics and by broth microdilution methods against 3 antibiotics, 7 disinfectants and 11 herbal medicines. LD experiment showed up to 80% of fish mortality, skin darkness, ulcers, hemorrhage, lethargy and hypo/anorexia in all groups, with exception of control. The LD₁₀,₅₀,₉₀ and ₉₉ were established in 4.1 × 10⁷, 8.8 × 10⁷, 1.9 × 10⁸ e 3.6 × 10⁸ CFU/mL, respectively. Ceftriaxone, florfenicol, oxytetracycline and thiamphenicol were considered promising against A. hydrophila. All herbal medicines were classified as bactericides, but clove Eugenia caryophyllata and cinnamon Cinnamomum zeylanicum displayed strongest activities. Among disinfectants, malachite green was the only that did not present acceptable values, discouraging its use. In conclusion, Koch's postulate was fulfilled and tambaqui entered to the vast list of A. hydrophila hosts and promising results of chemical substances were provided, contributing to motile Aeromonas septicemia (MAS) control.

Factors associated with severity of naturally occurring piscirickettsiosis in netpen- and tank-reared juvenile Atlantic salmon at a research aquarium in western Canada

The opportunistic examination of factors associated with an outbreak of piscirickettsiosis (SRS) is described in Atlantic salmon Salmo salar post-smolts held in an open netpen or in tanks supplied with raw sea water at a research aquarium in western Canada. During the outbreak, seawater temperature was significantly higher and salinity significantly lower in the netpen compared with the tanks. Mortality in the netpen began approximately 3 weeks prior to that in the tanks, and cumulative mortality in the netpen (34%) was significantly higher than in the tanks (12%). Piscirickettsia salmonis was confirmed by qPCR in tissues from moribund and dead fish and from colonies grown on enriched blood agar medium. Neither P. salmonis nor SRS were observed in salmon held concurrently in UV-irradiated sea water. The elevated mortality was curtailed by treatment with oxytetracycline. These observations further indicate warmer, less saline and periodically hypoxic seawater are risk factors for SRS. UV irradiation of sea water is shown to be a tool for SRS management in fish-holding facilities.